Gaius Marius Victorinus

The Greeks call “to be” ousian (substance) or hypostasin; we call it in Latin by one term, substance; and a few Greeks use ousian (substance) and rarely; all use hypostasin (hypostasis). Certainly one differs from the other, but for the moment let us omit this.The divine Scripture has often used hypostasin in Greek, substance in Latin. And it has said of the substance of God in the prophet Jeremiah “that if they had stood in the substance of the Lord they would have seen my word.” But what is it “to stand in the substance”? To know the substance of God, which is “true light,” which is infinite Spirit. If they had known that, they would have known the Logos of the Lord; that is, “they would have seen the word” of the Lord. And shortly after, the same Jeremiah uses the same words.
David says, “And my substance is in the lower regions of the earth.” He speaks also of God and says “substance.” And it is clear what this is.
The apostle says to the Hebrews, “He who is the character of his substance.” He said that Christ is the character of the substance of God. There are many other examples. But what is the point of all this? To show that the word substance is in Scripture and is used of the substance of God.